Synthesis of Mg-Fe-Cl hydrotalcite-like nanoplatelets as an oral phosphate binder: evaluations of phosphorus intercalation activity and cellular cytotoxicity.

The patients with end-stage of renal disease (ESRD) need to take oral phosphate binder. Traditional phosphate binders may leave the disadvantage of aluminum intoxication or cardiac calcification. Herein, Mg-Fe-Cl hydrotalcite-like nanoplatelet (HTln) is for the first time characterized as potential oral phosphate binder, with respect to its phosphorus uptake capacity in cow milk and cellular cytotoxicity. A novel method was developed for synthesizing the Mg-Fe-Cl HTln powder in different Mg(2+): Fe(3+) ratios where the optimization was 2.8:1. Addition of 0.5 g Mg-Fe-Cl HTln in cow milk could reduce its phosphorus content by 40% in 30 min and by 65% in 90 min. In low pH environment, the Mg-Fe-Cl HTln could exhibit relatively high performance for uptaking phosphorus. During a 90 min reaction of the HTln in milk, no phosphorus restoration occurred. In-vitro cytotoxicity assay of Mg-Fe-Cl HTln revealed no potential cellular cytotoxicity. The cells that were cultured in the HTln extract-containing media were even more viable than cells that were cultured in extract-free media (blank control). The Mg-Fe-Cl HTln extract led to hundred ppm of Mg ion and some ppm of Fe ion in the media, should be a positive effect on the good cell viability.

Improvement in dental porcelain bonding to milled, noncast titanium surfaces by gold sputter coating.

PURPOSE: This study evaluated the adherence of dental porcelain to a milled, noncast titanium (Ti) surface with a gold sputter coating to evaluate a possible new practical surface treatment for enhancing the bond strength between Ti and porcelain. MATERIALS AND METHODS: Milled, noncast Ti strips were created by computer-aided design and manufacturing processes. The milled, noncast Ti strips were sandblasted with alumina particles and were then sequentially subjected to gold sputter coating treatments of 150- and 300-second duration. Low-fusion dental porcelain was then sintered onto the surface-treated Ti strips. The bond strengths of the Ti/porcelain specimens were evaluated using a three-point bending test (ISO 9693). Surface characterizations of the specimens were carried out with X-ray photoelectron spectrometry, scanning electron microscopy, and energy dispersive X-ray spectroscopy. RESULTS: The results indicated that the bond strengths of all the Ti/porcelain groups were greater than the minimum requirement (25 MPa) as prescribed by ISO 9693. The gold sputter coating increased the oxidation resistance (or decreased the oxide content) of the Ti surface during porcelain sintering, which positively affected the bond strength of Ti/porcelain (approximately 36 MPa) compared to the untreated Ti/porcelain specimen (approximately 29 MPa). The fracture morphologies of all the Ti/porcelain groups revealed an adhesive bond failure as the interfacial fracture mode between the Ti and the porcelain. CONCLUSIONS: A practical and simple sandblasting/gold sputter coating treatment of Ti surfaces prior to porcelain sintering significantly strengthens the bond between the milled, noncast Ti and the dental porcelain.